Lindsay Lohan as Cady Heron

Rachel McAdams as Regina George

Lizzy Caplan as Janis Ian

Lacey Chabert as Gretchen Wieners

Amanda Seyfried as Karen Smith

Daniel Franzese as Damian

Jonathan Bennett as Aaron Samuels

Rajiv Surendra as Kevin Gnapoor

Tina Fey as Ms. Norbury

Tim Meadows as Mr. Duvall

Ana Gasteyer as Cady's Mom

Neil Flynn as Cady's Dad

Amy Poehler as Mrs. George

Dwayne Hill as Coach Carr

Diego Klattenhoff as Shane Oman

Molly Shanahan as Kristen Hadley

Elana Shilling as Spelling Girl

Graham Kartna as Homeschooled Boy

Ely Henry as Homeschooled Boy

David Aherne as Homeschooled Boy

Ayo Agbonkpolo as African Warrior

Jonathan Malen as Kristen's Boyfriend

Jeff Moser as "Farting" Guy

Miranda Edwards as Michigan Girl

Les Porter as Chemistry Teacher

Eve Crawford as English Teacher

Jack Newman as History Teacher

Michelyn Emelle as Music Teacher

Bathsheba Garnett as German Teacher

Ky Pham as Trang Pak

Danielle Nguyen as Sun Jin Dinh

Daniel DeSanto as Jason

Alisha Morrison as Lea Edwards

Chris Anton as Huge Guy

Jan Caruana as Emma Gerber

Wai Choy as Mathlete Tim Pak

Julia Chantrey as Amber D'Alessio

Jacky Chamberlain as Giselle Sgro

Olympia Lukis as Jessica Lopez

Stefanie Drummond as Bethany Byrd

Kristen Bone as Short Girl

Jessie Wright as Cady 5 Years Old

Tyson Fennell as Nfume

Stephan Dickson as Animal Dancer

Andreja Punkris as Animal Dancer

Noelle Boggio as Animal Dancer

Jordan Dawe as Animal Dancer

Alexandra Stapley as Taylor Wedell

Laura de Carteret as Mrs. Wedell

Nicole Crimi as Kylie George

Erin Norah Thompson as Dawn Schweitzer

Dan Willmott as Mr. George

Michelle Hoffman as Kissing Girl

Valerie Casault as Kissing Girl

Sharron Matthews as Joan the Secretary

Jo Chim as Salesperson

Randi Lee Butcher as Skater Girl

Erin Jarvis as Skater Girl

Kaylen Christensen as Jock Girl

Jill Morrison as Crying Girl

David Sazant as Marymount Captain

Clare Preuss as Caroline Krafft

Bruce Hunter as Mathlete Moderator

Megan Millington as Junior Plastic

Tara Shelley as Junior Plastic

Shannon Todd as Junior Plastic

David Reale as Glenn Coco (uncredited)

Krysta Carter as Wannabe (uncredited)